Lubricant



Patented Apr. 9, 1946 LUBRICANT Thomas E. Sharp, Chicago, 111., amino:to

Standard Oil Company, Chicago, Ill., a corporation of Indiana Drawing.Application November 30, 1843,

Serial No. 512,385

14 Claims.

This invention relates to improved protective coatings and lubricants.More particularly it relates to compounded lubricants which have, inaddition to valuable lubricating properties, the property of preventingcorrosion of metal surfaces.

Metallic equipment,'especially iron and steel equipment, exposed to theatmosphere for conslderable periods or time without operation ire=quently develops considerable corrosion, sulll= cient in many cases toimpede subsequent operation of the equipment and to reduce its operatins life.

The above observations apply with particular force to internalcombustion engines and other equipment exposed to severely corrosiveatmos pheres, such a are encountered, fo example, on shipboard, incoastal areas, and in many indus= trial areas. Engines in militaryequipment, for example, in automobiles, tanks, trucks, airplanes,tractors, are often subjected to storage in a. corrosive environment forextended periods, for example. as deck cargo in transoceanic shipping.Furthermore, the operation of internal combustion engines, especiallyspark ignition engines. results in the production of gases which corrodevarious metal engine parts with which they come in contact. Particularlycorrosive gases are generated in the operation of internal combustionengines with fuels containing ethyl fluid.

Heretofore it has been proposed to protect metal surfaces from corrosionby the use of readily removable protective coatings known as slushingcompounds. Slushing compounds are petroleum rust preventives and areusually classifled as oils and greases, from the standpoints ofappearance, handling and service properties.

Lubricating oils which can also be used as rust preventlves, especiallyfor internal combustion engines, in addition to meeting the usualpecifications concerning viscosity, volatility, ash content. residualcarbon deposits, and pour point, must have the following additionalproperties:

1. Ability to protect metal surfaces from high humidity and moisturecondensation;

2. Ability to neutralize acidic corrosive materlals;

3. Ability to be readily applied to and removed from metal surfaces, e.g. relatively inaccessible parts of an engine assembly.

It is an object of this invention to provide compodtions which aflordprotection against corrosion to metal surfaces coated thereby. Anotherobject of this invention is to provide corrosion preventive lubricantsfor metallic equipment stored or operated in a corrosive environment.Still another object of this invention is to provide lubricants whichwill prevent the occurrence of corrosion in internal combustion engines.A iurther object or this invention is to provide rust preventivelubricants particularly adapted for the lubrication of ordnance. Yetanother object or this invention is to provide a method of preventingcorrosion on metal surfaces by the application thereto of novelprotective coatings or lubricants.

it will be apparent that practical specifications lewd on the propertiesdesired in rust preventive lubricants can hardly be absolute in nature,but relative standards, represented by certain tests have been oil'eredand have received rather wide acceptance. These tests will be describedbriefly. Unless otherwise indicated all tests are carried out uponpolished, cold-rolled, sandblasted S. A. E. 1020 steel panels.

In the humidity test, the small steel panel are suspended in a. highlyhumid atmosphere, generally about 100% humidity, at a. fixed temperaturein a special cabinet and the time of initial corrosion of the panels isnoted. The humidity cabinet is provided with heating units and thermalregulators for automatic temperature control. A water level of twoinches or more i maintained in the bottom of the cabinet to assure highhumidity at all times. The steel panels are coated by dipping into therust preventive material and are suspended by glass hooks from a glassrod running across the top of the humidity cabinet. Generally from 1 to1.5 complete changes of air per hour are provided in the cabinet. Theminimum acceptable period of protection offered by the rust preventivematerial in the humidity cabinet test is determined in accordance withthe severity of the contemplated service conditions under which the rustpreventive material will be applied.

A number of hydrobromic acid tests have been designed to measure theability of rust preventive lubricants to neutralize acidic corrosivematerials. particularly the acidic products of combustion of internalcombustion engines. In a well recognized hydrobromic acid test,duplicate steel panels, such as are used in humidity cabinet tests, areswirled for a short time (usually either so or 60 seconds) in anemulsion prepared by vigorous agitation of a mixture of one part ofaqueous hydrobromic acid and nine parts of the rust preventivelubricant. Very dilute aqueous hydrobromic acid is used. generallyeither 0.1 or 55 0.2%. The duplicate panels are then stored in a woodblock support in the laboratory atmosphere for four hours and thensubjectedto a 24 hour test period in a humidity cabinet, as generallydescribed above. After exposure in the humidity cabinet the duplicatepanels are examined for evidence of corrosion or pitting.

I have found that compositions comprising an ester of an anhydroalkitoland a lubricant possess the combination or properties desired incorrosion preventive lubricants. I have further found that soaps ofpreferentially oil-soluble petroleum sulronic acids constitute a usefuladdition when added in small proportions to corrosion preventivelubricants containing an ester of an anhydroalkitoi.

By an anhydroalkitol I mean to designate a product of intramoleculardehydration of an alkitol. By an alkitol, I intend to denote apolyhydric alcohol having at least four carbon atoms and at least fourhydroxyl groups. Alkitols can be produced by the hydrogenation oipolyhydroxy aldehydes or ketones which occur in nature as sugars orsaccharides. Depending on the spatial configuration of the polyhydricalcohol, it can be either optically active or optically inactive, dueeither to the presence or a meso form of the molecule or to racemicmixtures oi optically active molecules. Exemplary alkitols are theerythritols; pentitols: arabitol, adonital, xylitol, prepared forexample by the hydrogenation of pentoses; hexane pentols, e. g.rhamnitol; hexitols: sorbitol, mannitol, dulcitol, iditol, talitol;heptane hexols, e. g. rhamnohexitol: heptitois: mannoheptitol,glucoheptitol, galaheptitol; ctitols: gluco-octitol, manno-octitol;nonitols, e. g. glucononitols, and the like.

The alkitols readily undergo intramolecular dehydration to produceanhydroalkitols, which are polyhydric cyclic ethers. When one moleculeof water is lost from an alkitol by intramolecular dehydration, apolyhydric monocyclic ether which I designate as a monoanhydroalkitol oralkitan is produced. When two molecules of water are lost from analkitcl by intramolecular dehydration, a hydroxy bicyclic ether which Idesignate as a dianhydroalkitol or alkide is produced.

Intramolecular dehydration or etheritlcation generally results in theproduction oi 4- to 7 membered cyclic ether, or oxido, rings. The 3-membered cyclic ether ring is sometimes called the oxidopropan ring. The4-membered ring is usually called the furan ring. The 5-membered ring isusually called the pyran ring. In general, there are manifoldpossibilities for intramolecular dehydration of alkitols, especially ofthe higher alkitols, such as hexitols, heptitols and the like. In thehigher alkitols it is conceivable that there is some possibility offorming even tricyclic ethers.

It will be appreciated that whenever the terms "alkitan" and alkide" areused, or whenever specific alkitans and alkides are designated, thatthese terms do not necessarily mean a single chemical compound but mayrefer to a mixture of several anhydroalkitol derivatives fallingtherein.

In order to demonstrate the meaning of the nomenclature given above, itwill be applied to the alkitol known as sorbitol, which is generallyproduced by the hydrogenation of glucose. Sorbitol has the followingstructure:

Upon intramolecular dehydration with the loss of one molecule of water,sorbitol can form a variety oi cyclic monoethers, but generally the mainproduct is an ether containing a furan ring: thus,

nocncnon In acsoncmon and no-cn-cnon somcn n-cmon In addition 4-, 6- and7-membered oxido rings may be produced to some extent:

once noon cnon s, n-cnion o noon-anon no a non H: H: o

HOCHCH CH:

H! H non Another dianhydrosorbitol may have the following structure:

o\ W/ \CHI C lHOCH-CHOH 1 have found that esters oi anhydroalkitois canbe compounded in small proportions with lubricants to produce corrosionpreventive lubricants. Esters suitable for the purposes of my inventioncan be obtained by esterltying anhydroalkitols by conventionalesteriflcation procedures. The acid components of the esters may bederived from a variety oi acids, such as the aliphatic carboxylic acids,e. g. fatty acids, or aliphatic carboxylic acids containing abranched-chain structure and/or an odd number of carbon atoms; cycliccarboxylic acids, e. g. cycloaliphatic carboxylic acids or naphthenicacids; aromatic carboxylic acids, alkylaromatic carboxylic acids.aralkyl carboxylic acids, rosin acids; sultonic acids, such as alh'l oraryl suli'onic acids, and the like.

I prefer to use esters ct anhydroalkitols and fatty acids for thepurposes oi my invention.

Particularly suitable esters are derived from the unsaturated fattyacids, particularly olelc acid.

Either part or all of the free hydroxyl groups available foresteriiication in the anhydroalkltol can be esterifled to produceproducts for the purposes of my invention. However, I have found thatsuperior products are obtained when part only of the free hydroxylgroups in anhydroaliritols are esterifled, and preservative andcorrosion preventive lubricants containing partial esters, particularlymono-esters of anhydroaikitols constitute a preferred product of myinvention.

Also useful for the purposes of my invention are the products obtainedby reacting partial esters of anhydroalkitols with alkylene oxides, suchas ethylene oxide or propylene oxide to produce polyoxyalkylenederivatives.

It will be appreciated that although a wide variety and large number ofesters of anhydroalkitols are available for use in corrosion preventivelubricants and protective coatings, they are not all preciselyequivalent. The choice of a particular ester for compounding inaccordance with the principles of my invention, will depend on thenature of the base stocks, 1. e. whether it is an oil, grease, wax,etc., the solubility of the particular ester in the selected base stock,the severity of service conditions which is contemplated, the eostsinvolved, etc.

The esters which are useful for the purpose of my invention can becompounded with a wide variety of hydrocarbon lubricating oils, whichmay also contain additions oi animal, vegetable or marine oils. Theesters can also be compounded with lubricating greases, by which I meanssolid or gel-like dispersions of soaps in hydrocarbon lubricating oils,or with waxes, e. g. paraflin wax. petrolatum, or ester-type waxes.

In general, esters of anhydroalkitols can be compounded with base stocksin proportions in the range of about 0.5% to about by weight. preferablyabout 1 to about 10% by weight, based on the total composition. It isgenerally preferable that the particular ester chosen for use he solublein the base stock in the proportions which it is desired to use. In theevent that the particular ester which it is desired to use is notsumciently soluble in the base stock, the use of conventionalsolubillzation or dispersion techniques may become necessary.

The following examples will serve to illustrate my invention:

Example 1 Sorbitan mono-oleate can be prepared, for example, byintrarnolecular dehydration and esterification of a three-fold molecularexcess of technical sorbitol syrup with oleic acid from white oleine bytreatment under a blanket of inert gas such as CO2. at about 500" F. Arust preventive lubricating oil particularly adapted for the protectionof aviation engines was prepared by dissolving 3.'I5% by weight ofsorbitan mono-oleate in a lubricating oil having a. viscosity index ofabout 95 and a viscosity of 120 seconds Saybolt Universal at 210 F. Therust preventive oil passed the humidity cabinet test described above,affording ample protection to sandblasted steel strips for 150 hours ina cabinet operating at 120 1". at 100% humidity. The rust preventive oilwas likewise subjected to the hydrobromic acid test employing 0.2hydrobromic acid in emulsion and swirling time of 60 seconds and foundto afford sumclent protection.

trample Z A rust preventive lubricant adapted for the protection andlubrication of internal combustion engines was prepared by compounding5% by weight of sorbitan mono-oieate with 82% by weight of a lubricatingoil having a viscosity of 4'? seconds Baybolt Universal at 210 F. and38% by weight of a lubricating oil having a viscosity of 94 secondsSaybolt Universal at 210 F. The compounded oil thus prepared passed ahumidity cabinet test of 50 hours duration at 100 F. and 95-100%humidity. the air in the cabinetbeing circulated at the rate of 1-1.5complete changes per hour. It likewise passed the hydrobromlc acid testemploying 0.1% aqueous hydrobromic acid in the emulsion and a swirlingperiod of 60 seconds.

When tested in a spark ignition engine for six hours at about 2600 R. P.M. at a crankcase oil temperature of 250 I". it was found that there wasless than 200 mg. loss per whole bearing. whereas a loss of 500 mg. iscommonly tolerated in this type of product.

I have found that soaps of preferentially oilsoluble petroleum sulfonicacids constitute desirable addants to rust preventive lubricants andprotective coatings containing esters of anhydro-alkitols.

Petroleum sulfonates are soaps of sulfonic acids obtained by thetreatment of petroleum oils with strong sulfuric acid, usually fumingsulfuric acid. The preferentially oil-soluble sulfonic acids remaindissolved in the acid-treated oil; they are commonly known as mahoganyacids. Although a wide variety of mahogany soaps can be used for thepurposes of this invention, I have found that they exhibit somevariation in eflicacy in my corrosion preventive lubricatingcompositions, depending on their method of preparation.

I have found that superior mahogany acids and soaps therefrom, for thepurpose of this invention, can be produced by treating distillates offrom about 50 seconds to about 1000 seconds or higher, and preferablyfrom about 200 to about 400 seconds Saybolt Universal viscosity at F.with from about 6 to about 9. pounds, and preferably from about 7 toabout 8 pounds of concentrated sulfuric acid, preferably fuming sulfuricacid, per gallon of oil.

The method of obtaining these desirable soaps of preferentiallyoil-soluble sulfonic acids derived from petroleum oils is illustrated bythe following example, which describes the preparation of a sodium soap.

A petroleum oil distillate having a Saybolt Universal viscosity at 100F. of from about 200 seconds to about 850 seconds is treated with fromabout '7 to about 8 pounds of fuming sulfuric acid per gallon of oil inone-half pound increments or "dumps." After the acid sludge from eachone-half pound acid dump is settled and withdrawn, the next one-halfpound of fuming sulfuric acid is added to the oil. The temperature ofthe oil before the fuming acid is added thereto is maintained belowabout 60 F. but due to the heat of reaction upon the addition of thesulfuric acid, the temperature of the oil may rise to from about 90 F.to about 100 F. After the required total amount of fuming sulfuric acidhas been added to the oil and the oil freed of acid sludge. the acidtreated oil containing oil-soluble sulfonic acids dissolved therein, isneutralized with a solution of sodium hydroxide. The aqueous alkalisolution is then separated from the oil solution containing dissolvedtherein sodium soaps of sulfonic acids and the latter then separatedfrom the oil by extraction with alcohol of about 60% strength. Thealcohol layer containing dissolved sodium sulfonates is then separatedfrom the oil and subsequently distilled to recover the alcohol andremove water. The crude sulfonic soap obtained in this manner containsfrom about 30% to about 60% sodium sulfonate, from about 30% to about60% oil, from about 1% to about water, and up to 10% of inorganic saltswhich may be removed by the procedure hereinafter described.

The above procedure may be modified after the acid sludge is removedfrom the acid-treated oil. The 011 containing dissolved sulfonie acidsis extracted with about 60% alcohol to remove the sulfonic acid; whichmay then be neutraliud with sodium hydroxide and subsequently freed ofthe alcohol by distillation.

The crude soaps of these preferentially oilsoluble sulionlc acidsobtained by the procedure described above may be freed of inorganicsalts by purification. This purification is preferably accomplished bydilution of the crude soap with from about A to about 10 parts,preferably 1 to 2 parts of 50% or higher strength alcohol, preferablyalcohol of 60 to 70% strength, and allowing the salts to settle whilemaintaining the mixture within the temperature range of 130 to 175 Pt,preferably 155 to 165 1". when the salts have settled the supernatantalcohol-soap layer is separated and the alcohol is recovered byconventlonal distillation procedure. By this method of purification thesalt content of the crude suli'onic soap can be readily reduced to 5% orless, e. g., to about 8.5%.

Although I have described a specific method for the preparation ofpetroleum sulfonic acids suitable for the purposes of my invention, itshould be understood that my invention i not restricted thereto, butthat suitable organic suifonates having similar properties can be used,however made.

Suitable soaps of preferentially oil-soluble petroleum sulfonic acidsfor the purposes of my invention include those of metals in groups I,II, III, IV, VI and VIII of the periodic table. Thus. for example, I canemploy the sodium, potassium, lithium, calcium, barium. tin, lead,aluminum. chromium, colbalt and nickel soaps of preferentiallyoil-soluble petroleum sulfonic acids. I can also employ the ammonium,alkylammonium and alkylolamine soaps of preferentially oil-solublepetroleum sulfonlc acids. It is not intended to imply that the widevariety of-sulfonates mentioned above are exactly equivalent for thepurpose of my corrosion preventive lubricatin compositions. Because oftheir relative cheapness and high eflicacy I prefer to use the sodiumsoaps. especially the sodium soaps of the preferred mahogany acids whosepreparation has been described above! The exact proportion of petroleumsulfonate to be used in my corrosion preventive lubricatin compositionswill vary with the particular sillfonate chosen for use and upon theseverity of the service conditions which are anticipated. In general, Ihave found that a useful range of commercial petroleum sulfonate isabout 5% to about 40%, the actual sulfonate soap content being in therange of about 2% to 16% based on the total composition, the remainderof the commercial aulfonate being associated oil and a small proortionof mineral salts.

The following example is adduced to illustrate the use of a soap ofpreferentially oil-soluble petroleum sulfonic acid together with anester of an anhydroalkitol to produce a preservative lubricant inaccordance with my invention. All percentages are by weight.

Example 3 U. S.patents:

m? Patentoo Patent am 1,903,011-- F.H.MacLaren... H.-. Iuneiii, 10341,003.01 Junal9,l03i 2.0mm?"-....do.- I Feb. 11.1mm 2,051,104--nmmmmnmarssmmne... Oct. l3, was

,055. F.H.Maoliaren.... Aug.10,1037

The compounded all passed a humidity cabinet test of 200 hours at F. and100% humidity. fresh saturated air beingdirected through the humiditycabinet at a rate between 1 and 1.5 complete chang s per hour.

As an indication that the rust preventive oil was not itself corrosive,it was found that it did not discolor a bright copper strip to a greaterextent than exposure to dry heat in an oven at 212 1''. for three hours.

The compounded oil was applied to a 0.50 caliber M2 basic aircraftmachine gun, the gun retained in a cold room at 70 1". for three hoursand then 26 rounds fired at full automatic fire. No stoppages occurredduring firing and an examination of the gun revealed that satisfactorylubrication was being obtained.

My novel rust preventive compositions may, in addition, containpolymeric thickener-s, viscosity index improvers, oiliness agents, pourpoint depressants, antioxidants and other well known types of additionagents. Although the use of my rust preventive compositions for theprotection of the interiors of internal combustion engines duringstorage has been emphasized, it is to be understood that they areapplicable generally for the protection of metal surfaces, as in gunbarrels and breeches, metal containers for pretroleum products or othercorrosive materials, idle machinery. finished machine parts andaccessories, stand-by or emergency equipment, and the like. The novelantirust agents of my invention may be compounded with a wide variety ofnormally liquid. semi-solid or solid lubricating or other media.

I claim:

1. A rust preventive lubricant comprising a major proportion of alubricating oil an ester of and minor corrosion inhibiting proportionsof an anhydroalkltol and a carboxyiic acid and an aliphatic soap of apreferentiall oil-soluble petroleum sulfonic acid.

2. A composition comprising a minor corrosion inhibiting proportions ofa partial ester of an anhydroalkitol and a fatty acid and a soap of apreferentially oil-soluble etroleum sulfonic acid, and a majorproportion of a lubricating oil.

3. A composition comprising a minor corrosion inhibiting proportions ofa partial ester of an alkitan and a fatty acid and a soap of apreferentially oil-soluble sulionic acid, and a major proportion of alubricating oil.

4. The method of inhibiting the corrosion of a metal exposed to acorrosive environment which comprises coating said metal with a sloshingcompound comprising minor corrosion inhibiting proportions of an esterof a hexitan and an unsaturated fatty acid and a soap of apreferentially 8. A rust preventive lubricating composition comprisingabout 5% of sorbitan mono-oleate, about 5% of a soap of a preferentiallyoil-soluble petroleum sulfonic acid, and a hydrocarbon lubricating oil.

9. A rust preventive lubricating composition comprising about 5% ofsorbitan mono-oleate,

about 5% of a soap of a preferential y oil-soluble petroleum sulfonicacid produced y treating a petroleum distillate having a viscosity inthe range of about 50 to about 1000 seconds Saybolt oil-solublepetroleum sulfonic acid produced by treating a petroleum distillatehaving a viscosity in the range of about 50 to about 1000 secondsSaybolt Universal at 100 F. with from 6 to about 9 pounds of strongsulfuric acid per gallon of dis tillates and a major proportion of ahydrocarbon lubricating oil.

5. A rust preventive lubricating composition comprising a majorproportion of a hydrocarbon lubricant and minor corrosion inhibitingproportions of an ester of an aliphatic carboxylic acid and ananhydroalkitol and a soap of a preferentially oil-soluble petroleumsulfonic acid produced by treating a petroleum distillate having aviscosity in the range of about 50 to about 1000 seconds SayboltUniversal at 100 F. with from about 6 to about 9 pounds of strongsulfuric acid per gallon of distillate.

6. A rust preventive lubricating composition comprising a majorproportion of a lubricating oil and minor corrosion inhibitingproportions of a partial ester of a fatty acid and a hexitan, and a soupof preferentially oil-soluble petroleum sulfonic acid.

'7. A rust preventive lubricating composition comprising a majorproportion of a lubricatingoil and minor corrosion inhibitingproportions of a mono-ester of a hexitan and oleic acid and a soap of:preferentially oil-soluble petroleum sulfonic ac Certificate Patent No.2,398,193.

Universal at F. with from about 6 to about 9 pounds of strong sulfuricacid per gallon of distillate, and a hydrocarbon lubricating oil.

10. A rust preventive lubricant comprising a major proportion of alubricating oil, a minor corrosion inhibiting proportion of a partialester of an anhydroalkitol and an aliphatic carboxylic acid, and a soapof a preferentially oil-soluble petroleum sulfonic acid.

11. A rust preventive lubricant comprising a major proportion of alubricating oil, between about 0.5 and about 15% of a partial ester ofan anhydroalkitol and an aliphatic carboxylic acid, and between about 5%and about 40% of a soap of a preferentially oil-soluble petroleumsulfonic acid.

12. A composition comprising a minor, corrosion inhibiting proportion ofan ester of an anhydroalkitol and a fatty acid, a soap of apreferentially oil-soluble petroleum sulfonic acid, and a lubricatingoil.

13. A composition comprising between about 0.5% and about 15% of anester of an anhydroalkitol and a fatty acid, between about 5% and about40% of a soap of a preferentially oil-soluble petroleum sulfonic acid,and a lubricating oil.

14. A composition comprising a minor, corrosion inhibiting proportion ofan ester of an anhydroalkitol and an'unsaturated fatty acid, a soap of apreferentially oil-soluble petroleum sulfonic acid, and a lubricatingoil.

THOMAS E. SHARP.

of Correction April 9, i946.

THOMAS E. SEAR? certifi d that error appears in the printed It is herebya correction as follows: Page 74, secon numbered patent requiring 71inclusive, claim 1, proportions of an anhydroalhitol and it instead andminor eo roston mhtbclmg n carlnyltc Md and a; with the Patent Oflice.

Signed and sealed this 4th day of June,

[ant] lmf th correction therein that the same may conform )3 an tar Ofand strike out the zarbox; 'c acid and an aliphatic" and insert onionsof an ester f at the said Letters Patent specification of the above dcolumn, lines 68 to minor corrosion inhibiting a'nh droalk'iiol andshould be read the record of the case in mm 4 Fird Accident Pm.-

preferentially oil-soluble etroleum sulfonic acid, and a majorproportion of a lubricating oil.

3. A composition comprising a minor corrosion inhibiting proportions ofa partial ester of an alkitan and a fatty acid and a soap of apreferentially oil-soluble sulionic acid, and a major proportion of alubricating oil.

4. The method of inhibiting the corrosion of a metal exposed to acorrosive environment which comprises coating said metal with a sloshingcompound comprising minor corrosion inhibiting proportions of an esterof a hexitan and an unsaturated fatty acid and a soap of apreferentially 8. A rust preventive lubricating composition comprisingabout 5% of sorbitan mono-oleate, about 5% of a soap of a preferentiallyoil-soluble petroleum sulfonic acid, and a hydrocarbon lubricating oil.

9. A rust preventive lubricating composition comprising about 5% ofsorbitan mono-oleate,

about 5% of a soap of a preferential y oil-soluble petroleum sulfonicacid produced y treating a petroleum distillate having a viscosity inthe range of about 50 to about 1000 seconds Saybolt oil-solublepetroleum sulfonic acid produced by treating a petroleum distillatehaving a viscosity in the range of about 50 to about 1000 secondsSaybolt Universal at 100 F. with from 6 to about 9 pounds of strongsulfuric acid per gallon of dis tillates and a major proportion of ahydrocarbon lubricating oil.

5. A rust preventive lubricating composition comprising a majorproportion of a hydrocarbon lubricant and minor corrosion inhibitingproportions of an ester of an aliphatic carboxylic acid and ananhydroalkitol and a soap of a preferentially oil-soluble petroleumsulfonic acid produced by treating a petroleum distillate having aviscosity in the range of about 50 to about 1000 seconds SayboltUniversal at 100 F. with from about 6 to about 9 pounds of strongsulfuric acid per gallon of distillate.

6. A rust preventive lubricating composition comprising a majorproportion of a lubricating oil and minor corrosion inhibitingproportions of a partial ester of a fatty acid and a hexitan, and a soupof preferentially oil-soluble petroleum sulfonic acid.

'7. A rust preventive lubricating composition comprising a majorproportion of a lubricatingoil and minor corrosion inhibitingproportions of a mono-ester of a hexitan and oleic acid and a soap of:preferentially oil-soluble petroleum sulfonic ac Certificate Patent No.2,398,193.

Universal at F. with from about 6 to about 9 pounds of strong sulfuricacid per gallon of distillate, and a hydrocarbon lubricating oil.

10. A rust preventive lubricant comprising a major proportion of alubricating oil, a minor corrosion inhibiting proportion of a partialester of an anhydroalkitol and an aliphatic carboxylic acid, and a soapof a preferentially oil-soluble petroleum sulfonic acid.

11. A rust preventive lubricant comprising a major proportion of alubricating oil, between about 0.5 and about 15% of a partial ester ofan anhydroalkitol and an aliphatic carboxylic acid, and between about 5%and about 40% of a soap of a preferentially oil-soluble petroleumsulfonic acid.

12. A composition comprising a minor, corrosion inhibiting proportion ofan ester of an anhydroalkitol and a fatty acid, a soap of apreferentially oil-soluble petroleum sulfonic acid, and a lubricatingoil.

13. A composition comprising between about 0.5% and about 15% of anester of an anhydroalkitol and a fatty acid, between about 5% and about40% of a soap of a preferentially oil-soluble petroleum sulfonic acid,and a lubricating oil.

14. A composition comprising a minor, corrosion inhibiting proportion ofan ester of an anhydroalkitol and an'unsaturated fatty acid, a soap of apreferentially oil-soluble petroleum sulfonic acid, and a lubricatingoil.

THOMAS E. SHARP.

of Correction April 9, i946.

THOMAS E. SEAR? certifi d that error appears in the printed It is herebya correction as follows: Page 74, secon numbered patent requiring 71inclusive, claim 1, proportions of an anhydroalhitol and it instead andminor eo roston mhtbclmg n carlnyltc Md and a; with the Patent Oflice.

Signed and sealed this 4th day of June,

[ant] lmf th correction therein that the same may conform )3 an tar Ofand strike out the zarbox; 'c acid and an aliphatic" and insert onionsof an ester f at the said Letters Patent specification of the above dcolumn, lines 68 to minor corrosion inhibiting a'nh droalk'iiol andshould be read the record of the case in mm 4 Fird Accident Pm.-

